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| e-docs > WebLogic Java Adapter for Mainframe > Introduction > BEA WebLogic Java Adapter for Mainframe Introduction |
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Introduction
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BEA WebLogic Java Adapter for Mainframe Introduction
To succeed in the new economy, your e-business depends on application integration. Specifically, integration of back-end systems with Web-based e-business applications. As the complexity of these Web-based applications evolve, the business transactions supported by these applications often require direct integration with existing mainframe legacy applications. In order to meet the rigorous demands for fast and flawless request execution, e-business transactions must integrate with mainframe applications in real time.
BEA WebLogic Java Adapter for Mainframe (hereafter referred to as WebLogic JAM) fulfills this requirement by providing bi-directional, request-response integration between Java applications and mainframe applications.
With WebLogic JAM, you can extend the life of existing mainframe applications by integrating them with J2EE applications running on WebLogic Server. Once configured and deployed, WebLogic JAM allows WebLogic Server applications to invoke or be invoked by mainframe applications. The following figure provides an overview of WebLogic JAM components and connectivity.
Figure 1-1 Typical WebLogic JAM Distributed Configuration
Business Benefits
BEA WebLogic JAM delivers the following business benefits to help your e-business grow and succeed:
The following sections provide an overview of the WebLogic Java Adapter for Mainframe product:
WebLogic Java Adapter for Mainframe Components
WebLogic JAM enables applications running on WebLogic Server and mainframe systems to interact using two main components:
These two WebLogic JAM Components work together to enable applications to communicate even though the applications are running in disparate environments. The following figure provides an overview of WebLogic JAM components and connectivity.
Figure 1-2 WebLogic JAM Environment
The Communication Resource Manager The Communications Resource Manager (CRM) is the WebLogic JAM component that manages communications resources. The CRM coordinates the flow of data between Java applications running on a WebLogic Server platform and applications running on a mainframe. The CRM uses SNA and TCP/IP communication protocols to communicate with the mainframe and WebLogic JAM Gateway respectively. TCP/IP protocols always flow between the WebLogic JAM Gateway and the CRM. SNA protocols always flow from the CRM to the mainframe and from VTAM on the mainframe to the CRM depending upon the configuration option. For a complete list of supported operating systems, refer to the BEA WebLogic Java Adapter for Mainframe Release Notes. The Gateway The WebLogic JAM Gateway component is a server that runs within WebLogic Server and communicates with the CRM using the TCP/IP protocol. The WebLogic JAM Gateway acts as a gateway to route requests and responses between WebLogic Server (Java) and mainframe systems, such as CICS and IMS. The Gateway component also forwards configuration information to the CRM at start-up. A WebLogic JAM Gateway used in conjunction with the CRM enables applications running on an instance of WebLogic Server to connect to back-end applications. Each WebLogic Server instance that needs to access back-end applications should have a WebLogic JAM Gateway defined for it. This WebLogic JAM Gateway routes requests received from Java client applications running on this instance of WebLogic Server to the CRM, which then will forward them to the back-end application. The Gateway also routes requests made by mainframe client applications that have come through the CRM to the necessary WebLogic Server applications.
WebLogic Java Adapter for Mainframe Features
The following sections describe features in WebLogic JAM:
WebLogic Server Support
BEA WebLogic JAM is used in conjunction with WebLogic Server to integrate existing mainframe applications with applications developed for WebLogic Server.
BEA WebLogic Server provides a tightly integrated, comprehensive infrastructure that delivers commerce, personalization, campaign management, enterprise integration, workflow management, and business-to-business collaboration.
BEA WebLogic Server supports a broad variety of clients, including Web browsers, wireless devices, and programmatic clients. On the server, BEA WebLogic Server supports the leading Unix, Linux, Windows, and mainframe operating systems. On the back-end, BEA WebLogic Server integrates with relational databases, message queues, and legacy systems.
BEA WebLogic Server implements the Java 2 Enterprise Edition (J2EE) platform specification that includes Servlets, Java Server Pages (JSPs), Enterprise JavaBeans (EJBs), Java Messaging Service (JMS), and other platform services. J2EE services provide access to standard network protocols, database, and messaging systems. When developing applications, developers can create, assemble, and deploy components that use these services.
WebLogic JAM enables Servlets, JSPs and EJBs to invoke CICS, IMS or batch applications that exist on your mainframe systems. WebLogic JAM also enables CICS, IMS, or batch applications to invoke EJBs or JMS services.
Communication Protocol Support
As previously mentioned, WebLogic JAM provides bi-directional, online request-response between Java applications and mainframe applications. WebLogic JAM facilitates Java applications making requests of mainframe services as well as mainframe clients making requests of Java services.
WebLogic JAM is especially useful as it enables Java applications to integrate with CICS programs using DPL and integrates with IMS programs using implicit APPC. Java client applications can link with CICS programs, and CICS clients can link with Java applications with the same ease as DPL between CICS programs on different regions. Similarly, Java client applications can communicate with IMS programs with the same ease as implicit APPC between different IMS programs. WebLogic JAM supports the following communications protocols:
Distributed Transaction Support
BEA WebLogic JAM supports distributed transactions for enterprise applications using the two-phase commit protocol. This support enables WebLogic JAM to coordinate operations against mainframe resources and resources in your WebLogic Server environment atomically.
Scalability
BEA WebLogic JAM can scale as your mainframe integration needs to grow. WebLogic JAM takes advantage of WebLogic Server clusters to provide load balancing and failover.
The following sections provide descriptions of the various WebLogic JAM scalability features.
Gateway Cluster Support
BEA WebLogic JAM enables clients within WebLogic Server to request mainframe services. Clients can run on any machine with network access to the WebLogic Server cluster hosting one or more WebLogic JAM Gateways. When clients request a mainframe service, this request will be transparently processed by one of the WebLogic JAM Gateways in the WebLogic Server cluster. This redundancy provides failover for the service request if one of the WebLogic JAM Gateways becomes unavailable. Thus, the WebLogic JAM Gateway cluster support enables reliable access to mainframe systems.
In terms of making your systems more scalable, WebLogic JAM takes advantage of the sophisticated load balancing features of WebLogic clusters for WebLogic Server to mainframe requests so that all load-balancing in WebLogic JAM occurs among a group of servers arranged in a WebLogic cluster. When requests are made to remote WebLogic JAM services, load balancing occurs among all WebLogic JAM Gateways in the cluster that offer the service. Mainframe to WebLogic Server request load balancing is accomplished by the WebLogic JAM CRM. The CRM load balances between all connected gateways without regard to their cluster arrangement.
Multiple-Gateway Support
BEA WebLogic JAM multiple gateway support provides a feature that enables a single instance of the CRM to service multiple instances of WebLogic JAM Gateways. As a result, multiple WebLogic Servers can share a single instance of the CRM as a common access point to mainframe systems.
The resulting configuration, administration, and operational requirements are similar to those for a single CRM, and resource requirements are substantially less than those for an equivalent multiple CRM configuration. This feature provides the following advantages:
Figure 1-3 Sample Multi-Gateway Non-Clustered Configuration
Multiple Region Support
Services provided to the WebLogic Server JAM application can be physically located on different CICS or IMS regions. The calling application does not have to know the physical location of the mainframe application. If a service is advertised on multiple regions, then WebLogic JAM provides load balancing and failover of the service across the multiple regions.
WebLogic Administration Console
BEA WebLogic JAM provides an easy-to-use interface for configuring and administering connectivity between WebLogic Server, CICS, and IMS application servers. WebLogic JAM provides an extension of the WebLogic Server Administration Console and presents a set of objects that can be manipulated in order to create or modify a configuration. These objects consist of Regions, Gateways, CRMs, Services, and Exports.
The WebLogic JAM Administration Console makes configuration information available by utilizing the Java Management Extensions (JMX) specification. JMX is an architecture specification for the management of enterprise applications. WebLogic Server provides a JMX implementation that allows applications to register manageable objects.
A start-up class of the WebLogic JAM product reads the XML configuration file and converts the information into JMX-manageable objects. This configuration information can then be remotely administered using the Administration Console and is available throughout the WebLogic Server domain to all instances of the WebLogic JAM product.
The console displays the WebLogic JAM components it administers, including Regions, Gateways, CRMs, Services, and Exports in a graphical tree in the left pane. The right pane displays details about the object selected in the left pane.
Figure 1-4 WebLogic JAM Administration Console
To use the console to configure or administer the WebLogic JAM product, select an item in the left pane, and then choose the desired informational tab in the right pane. The console displays the configurable attributes in the right pane. You can use the online help to find detailed information about the displayed attributes and fields. The console allows you to configure the connectivity between the WebLogic Server domain and multiple CICS or IMS regions and to define the configuration of multiple instances of WebLogic JAM, distributed across a WebLogic domain. For administrative purposes, the console allows you to administer the WebLogic JAM components as follows:
For complete information and instructions for configuring WebLogic JAM, see the BEA WebLogic Java Adapter for Mainframe Configuration and Administration Guide.
Configuration of a WebLogic JAM Gateway
BEA WebLogic JAM enables you to change configuration information dynamically, that is, while WebLogic JAM is running. In many cases, you do not need to restart WebLogic JAM for your changes to take effect. When a configuration attribute is modified, the new value is immediately reflected in both the current run-time value of the attribute and the persistent value stored in the XML configuration file.
Exceptions do exist. For example, if you change the CRM's listen port, the new port is not used until the next time you restart the CRM and it must be changed in the startup script or JCL for the CRM.
The Administration Console does a validation check on each attribute that is changed. The errors that are supported are out-of-range errors and datatype mismatch errors. In both cases, a message displays telling you that an error has occurred.
WebLogic JAM supports the following dynamic configuration changes:
eGen Application Generator
The eGen utility is an application development tool that assists in quickly integrating a mainframe application. This command line utility generates Java source code using a COBOL copybook and a declarative script file as input. The result is a working Java skeleton application that can be used as a basis for new applications or as an addition to an existing application. The eGen utility can generate Servlets, EJBs or stand-alone clients. All generated skeletons include code that implements connectivity and data translation to mainframe applications.
The four different types of Java application models that can be generated by the eGen utility are described as follows:
Samples
BEA WebLogic JAM includes a set of installation verification samples and a variety of other samples that you can use to demonstrate the broad range of WebLogic JAM features. The samples illustrate the interaction between Java applications and both applications running under CICS and applications running under IMS. The samples are also designed to step you through the configuration scenario that meets your specific configuration environment.
CrossPlex Support
BEA WebLogic JAM integrates CrossPlex in a seamless fashion to address customer requirements for reuse of any existing 3270 mainframe applications without the need for mainframe coding changes.
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